I also knew his playing more from his session work with Ian and Sylvia and if I remember rightly, Judy Collins. I remember one of my mates bringing in a record to rehearsal back in the late sixties and telling me this was what he wanted the backing to a song to sound like. There was a blazing run that apparently was played totally with the thumb. I nearly broke my fingers and went into deep despair over my attempts but never came close of course. I did learn a few chord runs that I could later use. We had one of those old record players that played at 16rpm which just about cut the speed in half while being close enough to tune to and copy ( it was an octave down of course).